Tamper resistant packaging is a high priority for many consumer product companies, and, in particular, consumer healthcare product companies where the contents of the package may be dangerous if contaminated prior to purchasing or if consumed by a minor without the supervision of an adult. Traditionally, heat sealed packaging has been known to be a very secure and tamper resistant format.
A clamshell is a one-piece container consisting of two halves joined by a hinge area which allows the structure to come together to close. Clamshells are often made of a shaped plastic material, in a way that is similar to a blister pack. Clamshell containers can be made of a variety of plastics such as polystyrene, polyester, PVC, among others. The material can be made by thermoforming or can be injection molded into the desired shapes. A single piece of material is used for the top and bottom with a “living hinge” that is integral with the material, rather than added separately. Clamshells can use a variety of means of closing or sealing. Some have self-locking tabs, snaps, or have a friction fit. Others use adhesive, pressure-sensitive tape, labels, staples, or are heat sealed, rf sealed, or ultrasonic sealed.
Heat sealing is the process of sealing one thermoplastic to another similar thermoplastic using heat and pressure. The direct contact method of heat sealing utilizes a constantly heated die or sealing bar to apply heat to a specific contact area or path to seal or weld the thermoplastics together.
The concept of heat sealing is well known in the art. Traditionally, heat sealing has required that the surfaces to be sealed be linear about the directional force (i.e. a flat surface). This provides limitations to the use of heat sealing on packaging that is more contoured and appealing to the consumer. For such complex packaging, other sealing methods are required that may not provide the tamper resistance and security that heat sealing provides, thus resulting in a conundrum for a company seeking high tamper resistance while also seeking appealing packaging to consumer. Thus, technology allowing for heat sealing on a undulating or curved surface is highly desirable.